Thyroiditis is an inflammation of the thyroid gland. There are many types of thyroiditis that cause various symptoms and health problems. Some types are chronic and progress slowly, whereas others are acute. Most types of thyroiditis are more common in women than men and tend to affect people over the age of 40.

An autoimmune disorder causes most cases of thyroiditis. Other causes include infections and certain medical treatments.

Types of thyroiditis include:

• Hashimoto's thyroiditis. The most common thyroid disorder in the United States and the leading cause of hypothyroidism. This autoimmune condition often comes on slowly, unfolding over months or even years.
  
  
• Painless (silent) thyroiditis. Initially, often causes a temporary increase in levels of thyroid hormones in the bloodstream (transient thyrotoxicosis) before hormone levels fall below normal (transient hypothyroidism). In most cases thyroid levels eventually return to normal. When thyrotoxicosis occurs, it can cause symptoms of hyperthyroidism.
  
  
• Postpartum thyroiditis. Similar to painless thyroiditis, except that it may occur only after a woman gives birth.
  
  
• Subacute thyroiditis. Similar to painless thyroiditis, except that it causes throat pain and typically is triggered by a viral infection.
  
  
• Infectious thyroiditis. Caused by a bacterial or viral illness.
  
  
• Drug-related thyroiditis. Caused by certain medications. It can lead to hypothyroidism and thyrotoxicosis.
  
  
• Radiation-induced thyroiditis. May occur as a result of using radioactive iodine to treat hyperthyroidism or radiation therapy to treat certain cancers. As with drug-induced thyroiditis, this type of thyroiditis can cause hypothyroidism and thyrotoxicosis.
  
  
• Riedel's thyroiditis. A rare but potentially serious disorder involving the formation of fibrous tissue in the neck.

Symptoms of thyroiditis may differ, depending on the type of thyroiditis involved and the condition it has caused in a patient’s body. Slow, chronic damage to cells of the thyroid gland causes symptoms of hypothyroidism such as fatigue, constipation and unexplained weight gain. Acute damage may cause symptoms that mimic hyperthyroidism, such as a rapid heartbeat, insomnia and unexplained weight loss.

Most physicians diagnose thyroiditis by using thyroid blood tests and radioactive iodine nuclear scans. Treatment options vary depending on the type of thyroiditis. Thyroid hormone replacement medications may be given to patients who experience hypothyroidism. Beta blockers, a type of antihypertensive, may be given to patients experiencing symptoms that mimic hyperthyroidism. There is no known method to prevent most cases of thyroiditis.

Thyroiditis is an inflammation of the thyroid gland, the butterfly-shaped gland that sits just below the area where an Adam's apple might be located at the front of the neck. The thyroid gland produces hormones that regulate a person's metabolism.

Any damage to the thyroid gland, such as inflammation, can disrupt its hormone production and affect body functioning. For example, if the thyroid gland fails to produce adequate levels of hormones for the body's needs, metabolism may slow, causing symptoms such as fatigue, constipation and unexplained weight gain. In this case, the thyroid gland is considered to be underactive, causing a condition known as hypothyroidism. This is commonly associated with slow, chronic damage to cells of the thyroid gland caused by thyroiditis.

On the other hand, rapid, acute damage to the thyroid gland caused by thyroiditis may cause hormones to leak out into the bloodstream. This causes a condition known as transient thyrotoxicosis (temporarily high levels of thyroid hormones in the blood). Symptoms may be identical to those of other forms of hyperthyroidism (e.g., rapid heartbeat, insomnia, unexplained weight loss), which involves increased metabolism. However, it is important to note that transient thyrotoxicosis caused by thyroiditis results from hormones stored in the thyroid leaking into the bloodstream. This differs from true hyperthyroidism, which is caused by an overproduction of hormone by the thyroid gland.

According to the American Association of Clinical Endocrinologists, 27 million Americans have thyroid problems that involve either underactive or overactive thyroid glands. Many cases are believed to remain undiagnosed.

Thyroiditis can cause serious damage to the thyroid, leading to various health problems. The Centers for Disease Control and Prevention (CDC) lists thyroiditis as a cause of death in a couple of cases per year.

There are many types of thyroiditis, with varying symptoms and causes. These include:

• Hashimoto's thyroiditis. This is the most common thyroid disease in the United States, according to the U.S. Department of Health and Human Services, and is the nation's leading cause of hypothyroidism. It is an autoimmune disease, meaning the body's immune system is hyperactive and mistakenly attacks the thyroid gland. It typically comes on slowly, often unfolding over a period of months or even years. In most cases, patients with Hashimoto's thyroiditis have hypothyroidism for the rest of their lives for which they must take medication. Some patients develop inflammatory thyroid nodules, small noncancerous growths in the gland.
  
  Patients with Hashimoto's thyroiditis have a modestly increased risk of developing one or more of the following disorders, according to the American Association of Clinical Endocrinologists (AACE): type 1 diabetes, Graves' disease (the leading cause of hyperthyroidism), Addison's disease (adrenal insufficiency), rheumatoid arthritis, lupus, pernicious anemia, vitiligo (a skin disease), thrombocytopenic purpura (a bleeding disorder) or premature ovarian failure (early menopause).
  
  About 14 million Americans, most of them women, have Hashimoto's thyroiditis, according to the AACE. It is named after the Japanese physician who described it in the early 20th century. Alternative terms include chronic lymphocytic thyroiditis and chronic thyroiditis.
  
  
• Painless (silent) thyroiditis. Usually, this condition initially causes a temporary rise in levels of thyroid hormones in the blood (transient thyrotoxicosis) before hormone levels temporarily fall below normal (transient hypothyroidism). This may cause mild symptoms that mimic hyperthyroidism for up to three months, followed by mild symptoms of hypothyroidism for up to 12 months. In about one-third of all cases, patients experience just one of these phases, according to the American Thyroid Association (ATA). Patients with painless (silent) thyroiditis usually experience a return to normal thyroid functioning within 18 months. However, about 20 percent of cases result in permanent hypothyroidism.
  
  
• Postpartum thyroiditis. This condition is virtually identical to painless (silent) thyroiditis, but it may occur only after a woman gives birth. In most cases, signs of inflammation first appear four to six months after delivery. The progression of this disease and its prognosis are similar to those of painless (silent) thyroiditis. Both conditions are thought to be autoimmune disorders, according to the American Association of Clinical Endocrinologists (AACE). Between 5 and 10 percent of pregnant women will experience postpartum thyroiditis, according to the National Institutes of Health. Up to 25 percent of pregnant women with type 1 diabetes will develop it, according to the AACE.
  
  Women at increased risk for this condition include those with a personal history of thyroiditis or immune system disorders, who test positive for antithyroid antibodies and who have a family history of thyroid problems. Postpartum thyroiditis is different from another disorder called Sheehan's syndrome, which can cause hypothyroidism following childbirth. This rare syndrome usually occurs in women who experience severe blood loss during childbirth that causes damage to the pituitary gland.
  
  
• Subacute thyroiditis. Also known as painful thyroiditis or DeQuervain's disease, it is similar to painless or postpartum thyroiditis in disease progression and prognosis. However, subacute thyroiditis is also a major source of pain in the thyroid gland. This pain usually persists throughout the transient thyrotoxicosis phase, which may appear as symptoms that mimic hyperthyroidism. Fever may also be present. Viral illnesses often cause subacute thyroiditis, particularly upper respiratory infections (e.g., the flu) and mumps. Permanent hypothyroidism occurs in 5 percent of cases, according to the ATA.
  
  
• Infectious thyroiditis. Also known as acute suppurative thyroiditis, it involves infection with a viral or bacterial illness, primarily the latter. Symptoms include thyroid gland pain, enlargement of the thyroid gland (goiter), as well as symptoms of hypothyroidism or other systemic illness.
  
  
• Drug-related thyroiditis. Taking certain medications can cause thyrotoxicosis (which symptoms mimic hyperthyroidism) and hypothyroidism. In many cases, the thyrotoxicosis lasts for only a short period before resolving. Hypothyroidism associated with medication use is likely to resolve once a patient stops using the drug causing the condition. Medications that may cause this condition include amiodarone (antiarrhythmic heart drug), lithium (treatment for bipolar disorder), and interferons and other cytokines (anti-inflammatory proteins).
  
  
• Radiation-induced thyroiditis. This type of thyroiditis may occur as a result of using radioactive iodine to treat hyperthyroidism or external-beam radiation therapy to treat certain cancers. As with medication-induced thyroiditis, this type of thyroiditis can cause thyrotoxicosis (mimicking symptoms of hyperthyroidism) and hypothyroidism. However, hypothyroidism associated with radiation typically is permanent.
  
  
• Riedel's thyroiditis. This rare but potentially serious disorder, also known as fibrous thyroiditis, involves the abnormal formation of fibrous tissue in the thyroid gland and nearby structures in the neck. It may be an autoimmune disorder or a fibrotic condition. Symptoms may include hoarseness, cough, difficulty swallowing (dysphagia), difficulty breathing (dyspnea) and underproduction of parathyroid hormone (hypoparathyroidism). It typically requires thyroid surgery.

Most types of thyroiditis are more common in women than men and also tend to more commonly affect people over the age of 40. A family history of thyroid disease, or personal history of thyroiditis or immune system disorders, may also increase a person's risk of thyroiditis.

Depending on the type of thyroiditis involved, additional potential risk factors include:

• Pregnancy
• Viral or bacterial illnesses (e.g., the flu, mumps)
• Use of certain medications (e.g., certain anti-inflammatory and antiarrhythmic drugs)
• Radiation therapy

An autoimmune disorder causes most cases of thyroiditis. These occur when the immune system mistakenly produces antibodies that attack healthy body tissue. In some cases, autoimmune disorders can attack cells and enzymes of the thyroid gland, reducing the thyroid gland's ability to produce adequate levels of hormones.

Hashimoto's thyroiditis, the most common thyroid disorder in the United States, is an autoimmune disorder. Postpartum thyroiditis and painless (silent) thyroiditis are also thought to be autoimmune conditions, according to the American Association of Clinical Endocrinologists. Additional autoimmune disorders that are associated with thyroiditis include:

• Type 1 diabetes
• Rheumatoid arthritis
• Autoimmune polyglandular syndrome

Viral and bacterial infections cause some types of thyroiditis. Use of certain medications or radiation also can cause thyroiditis. In addition, disorders such as Hashimoto's thyroiditis appear to have a genetic component. The cause of some types of thyroiditis remains unknown (idiopathic).

Symptoms of thyroiditis may differ, depending upon how the disease affects the thyroid gland.

In many cases, thyroiditis causes the thyroid gland to become underproductive, producing fewer hormones than the body requires, leading to hypothyroidism. Symptoms of hypothyroidism may include:

• Fatigue and sluggishness
• Enlarged thyroid gland (goiter)
• Puffiness of the face and ankles (due to edema)
• Increased sensitivity to cold
• Depression or other personality changes
• Forgetfulness
• Unexplained weight gain
• Constipation
• Muscle aches or muscle cramps

In some cases, thyroiditis may cause symptoms that mimic hyperthyroidism. This occurs when additional thyroid hormones leak out of the thyroid gland and into the bloodstream, causing thyrotoxicosis (high levels of thyroid hormones in the blood). These symptoms may include:

• Anxiety
• Enlarged thyroid gland (goiter)
• Irregular or rapid heartbeat
• Irritability
• Sudden, unexplained weight loss
• Insomnia
• Increased sweating and intolerance to heat
• Tremor

Throat pain, often in only one side of the neck, is an additional symptom that is typically present in subacute thyroiditis. Symptoms of hoarseness, coughing, difficulty swallowing (dysphagia) and difficulty breathing (dyspnea) may also appear in Riedel's thyroiditis.

To diagnose thyroiditis, a physician will review the patient's medical history and perform a physical examination. Thyroid blood tests may also be performed. These include thyroid-stimulating hormone (TSH) tests, T4 tests, T3 tests and autoimmune antibody tests. Testing for inflammatory processes in the body, such as the erythrocyte sedimentation rate (ESR), may also be conducted.

A radioactive iodine uptake test, also known as a thyroid nuclear scan and uptake, is also useful in diagnosing certain types of thyroiditis (e.g., subacute, painless, postpartum or infectious). In this test, the patient swallows radioactive iodine. The amount of radioactivity taken up by the thyroid gland helps a physician to determine how effectively the thyroid gland is functioning.

Thyroid imaging tests such as a thyroid scan may be recommended to help detect and monitor thyroiditis and related conditions such as hyperthyroidism or goiter.

In some cases, such as those that involve thyroid nodules or are hard to diagnose, a physician may recommend a fine-needle aspiration, which involves analysis of thyroid cells removed with a thin needle.

Treatment options for thyroiditis vary, depending on the type of thyroiditis involved and the condition it has caused in a patient's body. Medications are often used to treat thyroiditis. Thyroid hormone replacement medications may be given to patients who experience hypothyroidism. Medication may be taken for between six months and a year before the dosage is gradually lessened to monitor whether a patient requires continued treatment.

Beta blockers, a type of antihypertensive, may be given to patients who have high levels of thyroid hormones in their bloodstream (thyrotoxicosis). These medications, typically used to control high blood pressure, may relieve certain symptoms of hyperthyroidism (e.g., heart palpitations, tremors and shakes) that may accompany thyrotoxicosis. Patients usually need to use these medications for only a short period of time until symptoms go away.

Patients who experience pain of the thyroid gland can usually treat their symptoms with a mild over-the-counter anti-inflammatory medication. Patients with more significant pain may require prescription corticosteroids. Patients are urged not to take any medication without first consulting a physician. Possible risks of long-term use of corticosteroids include diabetes, osteoporosis, glaucoma and cataracts.

In many cases, patients who are diagnosed with thyroiditis require regular follow-up screenings so that a physician can monitor the health of their thyroid gland.

It is not known how to prevent autoimmune disorders, which cause most cases of thyroiditis. In cases where a patient's thyroiditis has a preventable cause, taking appropriate actions to prevent the cause may also prevent thyroiditis. For example, thyroiditis caused by the use of certain medications or treatments may be prevented by using alternative medications or treatments if possible. Taking steps to prevent viral or bacterial infections may also prevent some types of thyroiditis. Recent but as-yet-unconfirmed research suggests that supplementation with selenium may reduce the occurrence of certain types of thyroiditis.

Preparing questions in advance can help patients have more meaningful discussions with their physician regarding their conditions. Patients may wish to ask their doctor the following questions about thyroiditis:

1. What are the first signs that I may have thyroiditis?
   
   
2. How will you diagnose my thyroiditis?
   
   
3. How should I prepare for these tests?
   
   
4. What type of thyroiditis do I have?
   
   
5. What is the likely source of my thyroiditis?
   
   
6. What are my treatment options?
   
   
7. What are the risks and benefits of these treatments?
   
   
8. For how long will I need to take medications for my conditions?
   
   
9. How often will I need to be monitored so that you can track the progress of my condition?
   
   
10. Will I need to change my diet while on this medication?
    
    
11. What is my long-term prognosis?